diff --git a/include/ChangeLog b/include/ChangeLog
index 454863188..314913e9d 100644
--- a/include/ChangeLog
+++ b/include/ChangeLog
@@ -1,3 +1,8 @@
+2003-05-09  David Shaw  <dshaw@jabberwocky.com>
+
+	* types.h: Add typedef and initializer macro for 64-bit unsigned
+	type.
+
 2003-05-02  David Shaw  <dshaw@jabberwocky.com>
 
 	* cipher.h: Add constants for compression algorithms.
diff --git a/include/types.h b/include/types.h
index b41109ee5..83c0977da 100644
--- a/include/types.h
+++ b/include/types.h
@@ -21,6 +21,10 @@
 #ifndef G10_TYPES_H
 #define G10_TYPES_H
 
+#ifdef HAVE_INTTYPES_H
+/* For uint64_t */
+#include <inttypes.h>
+#endif
 
 /* The AC_CHECK_SIZEOF() in configure fails for some machines.
  * we provide some fallback values here */
@@ -99,12 +103,19 @@
   #undef u64	    /* maybe there is a macro with this name */
   #if SIZEOF_UNSIGNED_INT == 8
     typedef unsigned int u64;
+    #define U64_C(c) (c ## U)
     #define HAVE_U64_TYPEDEF
   #elif SIZEOF_UNSIGNED_LONG == 8
     typedef unsigned long u64;
+    #define U64_C(c) (c ## UL)
     #define HAVE_U64_TYPEDEF
   #elif SIZEOF_UNSIGNED_LONG_LONG == 8
     typedef unsigned long long u64;
+    #define U64_C(c) (c ## ULL)
+    #define HAVE_U64_TYPEDEF
+  #elif SIZEOF_UINT64_T == 8
+    typedef uint64_t u64;
+    #define U64_C(c) (UINT64_C(c))
     #define HAVE_U64_TYPEDEF
   #endif
 #endif